[PATCH v3 5/6] KVM: x86: hyperv: simplistic HVCALL_FLUSH_VIRTUAL_ADDRESS_{LIST,SPACE}_EX implementation

Vitaly Kuznetsov
2018-04-16T11:08:24Z

Implement HvFlushVirtualAddress{List,Space}Ex hypercalls in a simplistic
way: do full TLB flush with KVM_REQ_TLB_FLUSH and kick vCPUs which are
currently IN_GUEST_MODE.

Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
---
arch/x86/kvm/hyperv.c | 116 ++++++++++++++++++++++++++++++++++++++++++++++++++
arch/x86/kvm/trace.h | 27 ++++++++++++
2 files changed, 143 insertions(+)

diff --git a/arch/x86/kvm/hyperv.c b/arch/x86/kvm/hyperv.c
index fa26af1e8b7c..7028cd58d5f4 100644
--- a/arch/x86/kvm/hyperv.c
+++ b/arch/x86/kvm/hyperv.c
@@ -1301,6 +1301,108 @@ static u64 kvm_hv_flush_tlb(struct kvm_vcpu *current_vcpu, u64 ingpa,
((u64)rep_cnt << HV_HYPERCALL_REP_COMP_OFFSET);
}

+static __always_inline int get_sparse_bank_no(u64 valid_bank_mask, int bank_no)
+{
+ int i = 0, j;
+
+ if (!(valid_bank_mask & BIT_ULL(bank_no)))
+ return -1;
+
+ for (j = 0; j < bank_no; j++)
+ if (valid_bank_mask & BIT_ULL(j))
+ i++;
+
+ return i;
+}
+
+static __always_inline int load_bank_guest(struct kvm *kvm, u64 ingpa,
+ int sparse_bank, u64 *bank_contents)
+{
+ int offset;
+
+ offset = offsetof(struct hv_tlb_flush_ex, hv_vp_set.bank_contents) +
+ sizeof(u64) * sparse_bank;
+
+ if (unlikely(kvm_read_guest(kvm, ingpa + offset,
+ bank_contents, sizeof(u64))))
+ return 1;
+
+ return 0;
+}
+
+static int kvm_hv_flush_tlb_ex(struct kvm_vcpu *current_vcpu, u64 ingpa,
+ u16 rep_cnt)
+{
+ struct kvm *kvm = current_vcpu->kvm;
+ struct kvm_vcpu_hv *hv_current = &current_vcpu->arch.hyperv;
+ struct hv_tlb_flush_ex flush;
+ struct kvm_vcpu *vcpu;
+ u64 bank_contents, valid_bank_mask;
+ int i, cpu, me, current_sparse_bank = -1;
+ u64 ret = HV_STATUS_INVALID_HYPERCALL_INPUT;
+
+ if (unlikely(kvm_read_guest(kvm, ingpa, &flush, sizeof(flush))))
+ return ret;
+
+ valid_bank_mask = flush.hv_vp_set.valid_bank_mask;
+
+ trace_kvm_hv_flush_tlb_ex(valid_bank_mask, flush.hv_vp_set.format,
+ flush.address_space, flush.flags);
+
+ cpumask_clear(&hv_current->tlb_lush);
+
+ me = get_cpu();
+
+ kvm_for_each_vcpu(i, vcpu, kvm) {
+ struct kvm_vcpu_hv *hv = &vcpu->arch.hyperv;
+ int bank = hv->vp_index / 64, sparse_bank;
+
+ if (flush.hv_vp_set.format == HV_GENERIC_SET_SPARCE_4K) {
+ /* Check is the bank of this vCPU is in sparse set */
+ sparse_bank = get_sparse_bank_no(valid_bank_mask, bank);
+ if (sparse_bank < 0)
+ continue;
+
+ /*
+ * Assume hv->vp_index is in ascending order and we can
+ * optimize by not reloading bank contents for every
+ * vCPU.
+ */
+ if (sparse_bank != current_sparse_bank) {
+ if (load_bank_guest(kvm, ingpa, sparse_bank,
+ &bank_contents))
+ return ret;
+ current_sparse_bank = sparse_bank;
+ }
+
+ if (!(bank_contents & BIT_ULL(hv->vp_index % 64)))
+ continue;
+ }
+
+ kvm_make_request(KVM_REQ_TLB_FLUSH, vcpu);
+
+ /*
+ * It is possible that vCPU will migrate and we will kick wrong
+ * CPU but vCPU's TLB will anyway be flushed upon migration as
+ * we already made KVM_REQ_TLB_FLUSH request.
+ */
+ cpu = vcpu->cpu;
+ if (cpu != -1 && cpu != me && cpu_online(cpu) &&
+ kvm_arch_vcpu_should_kick(vcpu))
+ cpumask_set_cpu(cpu, &hv_current->tlb_lush);
+ }
+
+ if (!cpumask_empty(&hv_current->tlb_lush))
+ smp_call_function_many(&hv_current->tlb_lush, ack_flush,
+ NULL, true);
+
+ put_cpu();
+
+ /* We always do full TLB flush, set rep_done = rep_cnt. */
+ return (u64)HV_STATUS_SUCCESS |
+ ((u64)rep_cnt << HV_HYPERCALL_REP_COMP_OFFSET);
+}
+
bool kvm_hv_hypercall_enabled(struct kvm *kvm)
{
return READ_ONCE(kvm->arch.hyperv.hv_hypercall) & HV_X64_MSR_HYPERCALL_ENABLE;
@@ -1450,6 +1552,20 @@ int kvm_hv_hypercall(struct kvm_vcpu *vcpu)
}
ret = kvm_hv_flush_tlb(vcpu, ingpa, rep_cnt);
break;
+ case HVCALL_FLUSH_VIRTUAL_ADDRESS_LIST_EX:
+ if (unlikely(fast || !rep_cnt || rep_idx)) {
+ ret = HV_STATUS_INVALID_HYPERCALL_INPUT;
+ break;
+ }
+ ret = kvm_hv_flush_tlb_ex(vcpu, ingpa, rep_cnt);
+ break;
+ case HVCALL_FLUSH_VIRTUAL_ADDRESS_SPACE_EX:
+ if (unlikely(fast || rep)) {
+ ret = HV_STATUS_INVALID_HYPERCALL_INPUT;
+ break;
+ }
+ ret = kvm_hv_flush_tlb_ex(vcpu, ingpa, rep_cnt);
+ break;
default:
ret = HV_STATUS_INVALID_HYPERCALL_CODE;
break;
diff --git a/arch/x86/kvm/trace.h b/arch/x86/kvm/trace.h
index 47a4fd758743..0f997683404f 100644
--- a/arch/x86/kvm/trace.h
+++ b/arch/x86/kvm/trace.h
@@ -1391,6 +1391,33 @@ TRACE_EVENT(kvm_hv_flush_tlb,
__entry->processor_mask, __entry->address_space,
__entry->flags)
);
+
+/*
+ * Tracepoint for kvm_hv_flush_tlb_ex.
+ */
+TRACE_EVENT(kvm_hv_flush_tlb_ex,
+ TP_PROTO(u64 valid_bank_mask, u64 format, u64 address_space, u64 flags),
+ TP_ARGS(valid_bank_mask, format, address_space, flags),
+
+ TP_STRUCT__entry(
+ __field(u64, valid_bank_mask)
+ __field(u64, format)
+ __field(u64, address_space)
+ __field(u64, flags)
+ ),
+
+ TP_fast_assign(
+ __entry->valid_bank_mask = valid_bank_mask;
+ __entry->format = format;
+ __entry->address_space = address_space;
+ __entry->flags = flags;
+ ),
+
+ TP_printk("valid_bank_mask 0x%llx format 0x%llx "
+ "address_space 0x%llx flags 0x%llx",
+ __entry->valid_bank_mask, __entry->format,
+ __entry->address_space, __entry->flags)
+);
#endif /* _TRACE_KVM_H */

#undef TRACE_INCLUDE_PATH
--
2.14.3